This invention relates to paging receivers which can be individually and selectively called by radio signals.
Radio receivers of this type are carried by users and when such a receiver receive radio signals from a central office containing a special code, representing an individual call number assigned to that receiver, the receiver informs its users that he is being paged the user by means of a tone, light or vibration.
Under a special condition, for example, when the user is attending a conference or meeting, he operates a switch to store in a memory device the fact that he has received a radio signal and thereafter the user reads out the content of the memory device to confirm whether be has been paged or not.
Since the receiver is carried by the user, for example in a pocket of a suit, it is desirable to manufacture it as compactly as possible. Prior art receiver was constituted by a radio section which demodulates a radio signal received through an antenna, a call number setting unit that designates a call number, a decoder unit which controls the receiving operation and causes the receiver to respond only to paging messages with the designated call number, and informing or reporting devices which informs the user of a paging message call. Usually, these component elements are fabricated with intergrated circuits. If it is desired to enable a receiver of this construction to operate with a selected set of possible different functional options, it has been common in the prior art to assign each functional option a terminal on the decoder unit for individually determining whether or not that oprtion is selected by means of wiring that terminal either to a high or a low voltage level. Unfortunately, in such a receiver the number of the input terminals of the decoder unit increases with the increase in the number of selectable options, and, when the decoder unit is fabricated with an integrated circuit, it is often necessary to change its design each time the number of the selectable options is increased or changed. An increase in the number of terminals means an increase in the number of contacts to be soldered thus decreasing the reliability of the receiver and making it more difficult to maintain. Moreover, as above described, an increase in the number of the input/output terminals of the decoder unit means an increase of the size of the decoder unit, which runs contrary to the goal of decreasing, as far as possible, the size of the receiver.